I'm getting a tempo of about 96.86 BPM if you consider each repetition of the cycle to be a beat. Beyond that, I would just sit down at the keyboard and record a MIDI track, playing along with the rhythm on some suitable drum kit sounds (or even just silently by feel) for a few measures to find the rhythm within that beat. To me they sound like they'll fall on 16th triplets.... but, then, I'm prone to hear triplets in everything.
Incidentally, I found the "downbeat" to be about 25570 samples into the start of the track, but it looks like I converted a 96kHz WAV to 48kHz on import, so that's 51140 at the native rate.